PLL controlled two-phase travelling wave induction heater design

Induction heating is a fast, non-contact, clean, efficient, easy and precisely controllable heating technology. Due to these features, it is frequently preferred in industrial applications such as surface hardening, tempering, annealing, curing; in some medical applications and in domestic applications such as induction furnaces. In induction heating systems, the resonance frequency of the system changes and efficiency decreases due to the changing parameters of the workpiece depending on the temperature. In this thesis, keeping the induction heating system constantly at resonance has been achieved by using phase locked loop (PLL). Induction coil has been made of litz wire to reduce the skin effect. The problem of insufficient heat increase in the middle parts of the workpiece encountered in transverse flux induction heating systems has been solved by the two-phase traveling wave induction heater design. Ferrite magnetic flux concentrator has been used to reduce stray magnetic fields and direct the magnetic flux directly to the workpiece. Numerical analyses have been performed using the COMSOL Multiphysics program using the finite element method on 3D models. In the relevant program, a comparison of single and double coil transverse flux induction heating models with and without concentrators have been made. From the numerical analysis results, it has been observed that using traveling wave induction heating and magnetic flux concentrator for homogeneous heating on the workpiece surface in transverse flux induction heating systems increased the performance of the system. The system performance has been evaluated by measuring the temperature created on the workpiece by the induction heating system with a thermal camera. Thermal analyses have been performed using the Fluke Smartview program. The minimum, maximum, average values and standard deviations of the temperature values occurring on the workpiece surface, and temperature changes along the two horizontal axes have been examined. In addition, the time it took for a selected point to reach a certain temperature has been evaluated. Parametric scanning has been performed by changing the phase difference between the coil currents in the two-phase traveling wave induction heater model, and the most appropriate phase difference values have been determined for different situations.